Ladder having expandable members

ABSTRACT

A ladder including: first and second expandable members, each of the first and second expandable members including: a covering capable of expansion, the covering defining a cavity; and expansion means for expanding foam in the cavity in an expansion direction to expand the covering into a predetermined shape; each of the first and second expandable members having a plurality of holes; and a rung, having a first end disposed in each of the plurality of holes of the first expandable member and a second end disposed in a corresponding hole in the second expandable member.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to U.S. application Ser. No. 11/150,425,filed on the same day herewith, which is incorporated herein by itsreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to expandable devices andstructures and, more particularly, to devices and structures whichexpand at least in part due to expandable foam.

2. Prior Art

Collapsible devices are known in the art that generally make use ofmechanical linkages or telescoping parts to make a device more compact.However, such linkages and telescoping parts have a limit to which theycan compact and/or expand. Furthermore, such devices are not asmechanically stable as devices that do not expand.

Expandable structures are also known in the art. Such structuresgenerally use air or other gaseous pressure to expand an inflatablemember or collection of members. However, such structures suffer frompoor structural strength and are easily damaged if the skin of suchstructures is compromised (e.g., pierced or otherwise compromised). Insuch a situation, the failure of the structure is often catastrophic.

SUMMARY OF THE INVENTION

Accordingly, a ladder is provided. The ladder comprising: first andsecond expandable members, each of the first and second expandablemembers comprising: a covering capable of expansion, the coveringdefining a cavity; and expansion means for expanding foam in the cavityin an expansion direction to expand the covering into a predeterminedshape; each of the first and second expandable members having aplurality of holes; and a rung, having a first end disposed in each ofthe plurality of holes of the first expandable member and a second enddisposed in a corresponding hole in the second expandable member.

The covering can be pleated when compact.

The ladder can further comprise first and second endplates, the coveringbeing disposed between the first and second endplates.

The expansion means can comprise: a first inlet formed in one of thefirst and second endplates, the first inlet being in communication withthe cavity; and a source in communication with the first inlet forsupplying foam in a liquid state to the cavity via the first inlet. Inwhich case the ladder can further comprise: a second inlet formed in oneof the first and second endplates, the second inlet being incommunication with the cavity; and a gas source in communication withthe second inlet for supplying gas to the cavity via the second inletfor at least one of pre-expanding the covering and facilitating fillingof the cavity with the foam.

The ladder can further comprise bulge prevention means for preventingbulging of the covering in a direction other than the expansiondirection.

The ladder can further comprise one or more tensile elements disposed inthe cavity for carrying at least a portion of a tensile load on thefirst and second expandable members.

The expansion means can comprise: first and second capsules disposed inthe cavity, the first capsule having a first liquid therein, the secondcapsule having a second liquid therein, the first and second liquidswhen combined reacting to form the foam; and means for mixing the firstand second liquids. The means for mixing can comprise: the first andsecond capsules having a skin encapsulating the first and secondliquids, respectively; and a cable having the first and second capsulesformed thereon, the cable having a mixing means disposed on the cable,the cable being capable of being withdrawn through the cavity such thatthe skin is broken and the mixing means facilitates mixing of the firstand second liquids. The cable can further comprise: one or more wiresfor carrying at least a portion of a tensile load on the member, each ofthe one or more tensile elements being capable of being expanding in theexpansion direction and being connected to one of the first and secondendplates at a first end and being connected to the cable at a secondend; and means for fixing the second end to the other of the first andsecond endplates upon expansion of the one ore more wires.

The ladder can further comprise a grommet disposed in each of theplurality of holes. In which case, the ladder can further comprise aconnection means for connecting each of the grommets together such thatthey react to an applied force as a unitary member. The ladder canfurther comprise first and second endplates, the covering being disposedbetween the first and second endplates, wherein the connection meanscomprises a wire connected between each of the grommets and between atleast one of the first and second endplates and at least one of thegrommets. The wire can be connected between each of the grommets bywinding the wire around an outside circumference of the grommet.

The ladder can further comprise locking means for locking the rungs inthe plurality of holes.

Also provided is a method for forming a ladder. The method comprising:forming first and second expandable members used in constructing theladder, the forming of each of the first and second expandable memberscomprising: expanding a covering to define a cavity; and expanding foamin the cavity in an expansion direction to expand the covering into apredetermined shape; and connecting the first and second expandablemembers together by disposing a plurality of rungs therebetween.

The connecting can comprise: disposing a first end of each of the rungsin each of the plurality of holes of the first expandable member anddisposing a second end of each of the rungs in a corresponding hole inthe second expandable member.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the apparatus ofthe present invention will become better understood with regard to thefollowing description, appended claims, and accompanying drawings where:

FIG. 1 a illustrates an embodiment of an expandable structural member ina compact configuration.

FIG. 1 b illustrates the expandable structural member of FIG. 1 a afterexpansion.

FIG. 2 illustrates a schematic of a system for expanding the structuralmember of FIGS. 1 a and 1 b.

FIG. 3 illustrates a coupling for connecting structural members.

FIG. 4 illustrates an alternative embodiment for expanding thestructural member of FIG. 1 a.

FIG. 4 a illustrates an enlarged view of a portion of the structuralmember of FIG. 4.

FIG. 4 b illustrates a variation of the embodiment of the structuralmember of FIG. 4 in which the structural member is in a compactconfiguration.

FIG. 4 c illustrates the variation of the embodiment of the structuralmember of FIG. 4 b in which the structural member is in an expanded orelongated configuration.

FIG. 5 illustrates a structure built with expandable structural membersand panels.

FIG. 5 a illustrates a side view of two wall panels of the structure ofFIG. 5.

FIG. 5 b illustrates a partial sectional view through a wall/end wallpanel of the structure of FIG. 5 proximate an opening.

FIG. 5 c illustrates an expandable structural member having boltfasteners integral therein, the expandable structural member being in acompact configuration.

FIG. 5 d illustrates the expandable structural member of FIG. 5 c afterexpansion.

FIG. 5 e illustrates an alternative embodiment of the bolt fasteners ofFIGS. 5 c and 5 d.

FIG. 6 illustrates a bridge structure built with expandable structuralmembers and panels.

FIG. 6 a illustrates a side view of two adjacent ends of beams of thebridge structure of FIG. 6 having a rotatable joint therebetween.

FIG. 6 b illustrates a top view of the two adjacent ends of the beams ofFIG. 6 a before assembly thereof.

FIG. 7 a illustrates an expandable structural member after expansionwhere the structural member is in the form of a leg of a ladder.

FIG. 7 b illustrates a rung of a ladder.

FIG. 7 c illustrates a ladder built with the legs and rungs of FIGS. 7 aand 7 b, respectively.

FIG. 7 d illustrates a partial section of the leg of FIG. 7 c in acompact configuration as taken along line 7 e-7 e.

FIG. 7 e illustrates the partial section of the leg of FIG. 7 c in anelongated configuration.

FIG. 7 f is a partial sectional view of the ladder of FIG. 7 c as takenalong line 7 f-7 f.

FIG. 8 a illustrates a front view of an after expandable electronicdevice before expansion.

FIG. 8 b illustrates a side view of the electronic device of FIG. 8 abefore expansion.

FIG. 8 c illustrates the electronic device of FIGS. 8 a and 8 b afterexpansion.

FIG. 9 a illustrates a tank loaded in a cargo bay of an aircraft havingan expandable member at a lower surface thereof.

FIG. 9 b illustrates the tank of FIG. 9 a being deployed from theaircraft.

FIG. 9 c illustrates the tank of FIGS. 9 a and 9 b before it impacts asurface with the expandable member being expanded.

FIG. 10 a illustrates a sectional side view of an expanded structuralmember having shape restraint members for constraining the cross-sectionof the member to a predetermined shape.

FIG. 10 b illustrates a sectional view of the expanded structural memberof FIG. 10 a as taken along line 10 b-10 b.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Expandable foams are well known in the art. Typically such foams aremade by mixing two liquid parts, which react to form foam. Although, twoparts are typical, one part expanding foams are also known in the art.The reaction of the two parts is usually exothermic. The resulting foamsexpand in volume from up to 30 times the volume of the liquidconstituents. The liquids begin foaming almost instantly and can fullycure in a matter of minutes. However, both the beginning of foaming andthe curing time can be varied with the addition of additives. Additivescan also be added to make the resulting foam fire resistant orretardant. The resulting foams generally have good structural(compressive, tensile, shear, and flexural) strength and are alsobuoyant. For the most part, the resulting foams are closed cell and willresist absorption of water. Polyurethane is an example of a material ofcommonly used expanding foams. For example, a 2 lb density (per cubicfoot) urethane foam has an expansion rate of 30 times the liquid volume,a buoyancy of 60 lbs per cubic foot, 40 psi parallel compressivestrength, 30 psi tensile strength, 30 psi shear strength, and 50 psiflexural strength. A 4 lb density (per cubic foot) urethane foam has anexpansion rate of 15 times the liquid volume, a buoyancy of 58 lbs percubic foot, 90 psi parallel compressive strength, 110 psi tensilestrength, 70 psi shear strength, and 120 psi flexural strength. An 8 lbdensity (per cubic foot) urethane foam has an expansion rate of 8 timesthe liquid volume, a buoyancy of 54 lbs per cubic foot, 250 psi parallelcompressive strength, 225 psi tensile strength, 130 psi shear strength,and 350 psi flexural strength. A 16 lb density (per cubic foot) urethanefoam has an expansion rate of 4 times the liquid volume, a buoyancy of46 lbs per cubic foot, 580 psi parallel compressive strength, 450 psitensile strength, 230 psi shear strength, and 750 psi flexural strength.The expansion rate and time are dependent upon the ambient temperature.The rates given above are for optimal conditions of 75-80 degrees F.Lower temperatures will hinder the expansion and time rates of the foam.Other density foams are available and can be tailored to a specificapplication.

Referring now to FIGS. 1 a and 1 b, there is shown a structural memberin the form of a beam, generally referred to by reference numeral 100.The beam 100 is shown in FIG. 1 a in a compressed or compact form andshown in FIG. 1 b in an expanded or elongated form. Referring to FIG. 1a, the compact beam has first and second endplates 102, 104 which can beformed from rigid or semi-rigid materials, such as plastics and/ormetals. The shape of the endplates 102, 104 can be any cross-sectionalshape known in the art for use as a beam, such as rectangular or I-beamshapes.

The beam 100 further has a covering 106 of a material that can becompressed, such as by pleating the same, shown schematically at 108.The covering 106 can be a woven fabric and/or polymer sheet, and can bebullet proof or resistant, such as ballistic nylon or woven Kevlar. Thecover can also be elastic such that it can stretch to accommodate achange in length of the beam 100. Although the covering 106 is shownbridging the top and bottom of the endplates 102, 104 in thecross-section of FIG. 1 a, it is assumed to bridge all sides of theendplates 102, 104 to define a cavity 110. At least one of the endplates102 can have one or more inlets 112 a, 112 b for inputting at leastexpandable foam liquid(s) and possibly also a gas, such as air. The beam100 does not need the endplates 102, 104 in which case, the covering mayprovide a means to close the cavity 110. Furthermore, the endplates 102,104 do not have to extend along an entire width of the beam 100 and maybe formed of multiple rigid or semi-rigid members, such as a pluralityof grommets or washers formed on ends of the covering.

Referring now also to FIGS. 1 b and 2, the expanding foam liquid, whichcan be any of the two-part polyurethane's described above, is input intoone of the inputs 112 b from sources 114 a, 114 b (corresponding to eachof the two parts (A and B) of the expanding foam) through suitabletubing 115. The two parts are supplied to the inlet 112 b and mixed tostart a reaction therebetween. The mixing can take place at any time orlocation prior to entering the cavity 110 or at the entrance to thecavity 110. The mixing of two part expanding foam liquids is well knownin the art. The expanding foam 116 fills the cavity 110 and causes thebeam 100 to expand as shown in FIG. 1 b. As discussed above, suchexpansion can be as much as 30 times the volume of the liquids. A gas,such as air, from a supply 118 can also be introduced into the cavity110 via suitable tubing 119 through another of the inlets 112 a (orthrough the same inlet 112 b as the expanding foam liquids). The air canbe used to pre-expand the covering 106 such that the foam is free toexpand throughout the expanded cavity 110 and/or introduced during theintroduction of the expanding foam liquids to propel the same away fromthe inlets 112 a, 112 b so that the foam fully fills the cavity and doesnot only fill the cavity 110 proximate the inlets 112 a, 112 b. Theamount of expanding foam liquid introduced into the cavity 110 can bemetered so that it does not underfill or overfill the cavity 110 afterexpansion. Valving and pumps or other delivery devices are not shown inthe schematic of FIG. 2 for simplification and are assumed to be presentto the extent that they are necessary. The covering 106 can have ribs(not shown) to prevent bulging of the cover due to the expansion of thefoam. The bulging, if any, can be controlled with mechanical devices,such as forms of a roller for rolling the surface of the cover to spreadthe uncured foam evenly throughout the cavity.

After, the expanded foam is cured, the beam 100 can carry structuralloads and be used with other structural elements to form a structure.The foam 116, as discussed above, can be made with any additive known inthe art to tailor its properties, curing time, and othercharacteristics, such as being flame retardant. The resulting beam 100,as shown in FIG. 1 b can also have tensile elements integrated thereinfor aiding in carrying any tensile loads that may be exerted on the beam100. Such tensile elements can be wires 120 which are coiled orotherwise compressed (as shown in FIG. 1 a) when the beam 100 is in itscompact form and elongated (as shown in FIG. 1 b) when the beam is inits expanded form. The wires 120 can be attached to each of theendplates 102, 104 by any means known in the art, such as brazing (asdescribed below) or the like. The wires 120, in the elongated form, canhelp carry a tensile load exerted on the beam 100. Since beams generallyare subject to tensile loads on a lower portion, the wires 120 can beprovided only at a lower portion of the beam, as shown in FIGS. 1 a and1 b. However, the beam must then be correctly oriented when used.Therefore, the beam 100 can also have wires 120 at both the top andbottom portions of the beam 100 such that orientation is not necessary.The wires can be any material that can carry a tensile load, such asmetal or fiber. The wires 120 are best for carrying compressivestresses, e.g., on the top surfaces of beams or top panels and on thesurfaces of columns when subject to buckling. These “wires” 120 are bestto be flat strips, which are best to be oriented with the flat sidepointing upwards. Then, as a compressive load is applied, the foam onthe flat sides of the strip prevent its buckling, thereby allowing it tosupport compressive loads.

The wires 120 can also be a shape memory material that can change itsshape upon being heated over a transition temperature. Such shape memorywires 120 can have a compact shape (such as a coil) in the compactconfiguration of FIG. 1 a and can take a straight elongated shape uponbeing heated above its transition temperature. Upon taking the elongatedshape, such shape memory wires 120 can exert a force to at least aid theexpansion of the covering 106 during the introduction of the expandingfoam in the cavity 100. The exothermic reaction of the foam can be usedto heat the wires 120 over their transition temperature and cause thesame to take the elongated shape that at least aids the expansion of thecovering 106. The shape memory wires 120 can be used in place of or inaddition to the introduction of the air into the cavity 110.

Referring now to FIG. 3, the same shows end portions of beams 100.However, such beams 100 have endplates 102, 104 which arenon-perpendicular with respect to a long axis L of the beam 100 (unlikethe beam of FIG. 1 b in which the endplates are perpendicular withrespect to the long axis L). The beams 100 of FIG. 3 are useful to forma truss when connected together end-to-end. Each of the beams 100 has anendplate 102 on one end (e.g., the left end) and each has an endplate104 on the other end (e.g., the right end). The endplates 102, 104 havea means for interlocking by any means known in the art, such as oneendplate 104 having one or more hooks 122 and the other endplate 102having one or more corresponding latches 124. When the hooks 122 areengaged with the latches 124 the beams 100 are fastened together to forma truss assembly 200 (see FIG. 5). Many types of interlocking means areknown in the art and will not be discussed herein for the sake ofbrevity.

Referring now to FIG. 4, there is illustrated another embodiment of astructural member in the form of a beam, the beam being referred to byreference numeral 300 and being shown in the compact form in FIG. 4. Thebeam 300 of FIG. 4 is similar to that of FIGS. 1 a and 1 b except thatthe inlets 112 a, 112 b for introducing air and/or expanding foamliquid(s) are not necessary. In the embodiment of FIG. 4, the cavity 110is filled with capsules 302 or packets of the expanding foam liquids,(the liquids referred to by reference letters A and B where A is one ofthe two parts of the expanding foam liquids and B is the other). Thecapsules 302 can be arranged side-by-side and can alternate horizontallyand/or vertically as shown in FIG. 4. The capsules 302 have a skin 304or enclosure for holding the liquids (A and B) therein, such as a thinfilm of plastic. The volume of the liquids (A and B) in the capsules 302is that which is necessary to adequately fill the cavity 110 when thecovering 106 is expanded. The number of capsules 302 is a tradeoffbetween the amount of mixing and complexity. The greater the number ofcapsules 302, the more likely the two parts (A and B) will sufficientlymix. However, a great number of capsules 302 also adds to the complexityof the beam 300.

The beam 300 of FIG. 4 also comprises a means for mixing the liquids (Aand B) in the capsules 302. Such a means can rupture or otherwise breakthe skin 304 of the capsules 302 or chemically dissolve the skin ordissolve or otherwise breakdown the skin 304 with the application (orinterruption of) of a magnetic field or current. In the latterconfiguration, the skin 304 may be a thin rheological material that isbroken down (or liquefied) upon the removal of an applied magnetic fieldor current. In the embodiment of FIG. 4, the means for mixing theliquids comprises one or more cables 306 which are threaded through thecapsules 302 and sealed at the skins 304 to the cable 306. Preferably,the capsules 302 are formed on the cable 306 as a “necklace” anddisposed in the cavity 110. The cable 306 has a mixing means formed atone end thereof, such as an auger or brush 308 that will facilitatemixing of the liquids (A and B) as it is moved through the capsules 302.Although each cable 306 is shown with a single brush 308, two or moremay also be provided spaced along the length of the cable 306. Anotherend of the cable can have a finger loop 310 or other means for providinga grip of the cable 306. One of the end plates 104 has through holes 312corresponding to each of the cables for exposing an end of the cable 306on an exterior of the endplate 104. The through holes 312 can have asealing means, such as an o-ring 314 for preventing leakage of theliquids (A and B) and/or the expanding foam from the cavity 110. Whenexpansion of the structural member, such as the beam 300 is desired, theone or more cables 306 are grasped, at the finger loops 310 and pulledin the direction of Arrow A to rupture the capsules 302 and to drag themixing means 308 through the capsules to facilitate the mixing of theliquids (A and B). The mixture of the liquids (A and B) results in anexpanding foam and the expansion of the beam 300 into its expandedconfiguration. After curing of the foam, the beam 300 can be used aloneor in combination with other structural members to form a structure.

During assembly of such a beam 300, one endplate 102 and the covering106 are fastened together by any means known in the art, such as byadhesives or with the use of a securing frame 102 a (shown clearly inFIG. 4 a). The covering 106 is sandwiched between a surface 316 of theendplate 102 and a surface 318 of the securing frame and secured with afastener, such as a screw 320, a solvent, or an adhesive. The cable 306and capsule 302 “necklaces” are laid in the cavity 110 with the mixingmeans being proximate to the endplate 102 and without the finger loops310. The other endplate 104 is then secured to the covering by anymethods known in the art, such as with a securing plate 104 a similarlyto that described with respect to endplate 102 and securing plate 102 a.The cable ends are threaded through their corresponding holes 312 uponplacement of the endplate 104 and the finger loops 310 are placed on thecable ends by any means known in the art, such as by tightening setscrews (not shown) in the body of the finger loops 310 against the cableend. A means can be provide to prevent an accidental pulling of thecables 306 before the beam 300 is desired to be expanded, such as acover plate or film (not shown) disposed over the endplate 104 andfinger loops 310.

The structural member 300 of FIG. 4 can be configured to also havetensile elements integrated therein for aiding in carrying any tensileloads that may be exerted on the beam 300 similarly to that describedabove with regard to FIGS. 1 a and 1 b. As shown in FIG. 4 b, suchtensile elements can be wires 120 which are coiled or otherwisecompressed when the beam 300 is in its compact form and elongated (asshown in FIG. 4 c) when the beam 300 is in its expanded form. AlthoughFIGS. 4 b and 4 c illustrate one such wire 120, more than one can beprovided as discussed above. Furthermore, the wires 120 can be providedat a lower portion of the beam 300, which is subjected to a tensile loador the wires 120 can be provided at both upper and lower portions of thebeam 300 such that orientation of the beam 300 is not necessary. Asdiscussed above, the wires 120, in the elongated form, can help carry atensile load exerted on the beam 300. The wires 120 can be any materialthat can carry a tensile load, such as metal or fiber, and may be ashape memory material as discussed above. One end 120 a of the wires 120can be attached to the endplate 102 by any means known in the art, suchas by being disposed in a corresponding hole 120 b in the endplate 102and brazing 120 c or otherwise fastening the wire to the endplate 102.Another end 120 d of the wire 120 is attached to an end 306 a of a cable306. A fitting 322 can be disposed at a transition between the wire 120and the cable 306. The fitting 322 is fixed to the cable 306 and/or wire120 such that its movement along the wire and cable is fixed by anymeans known in the art. Upon pulling the cable 306, the cable 306 andmixing means 308 functions as discussed above, and the fitting 322 ispulled towards the other endplate 104 until the fitting 322 locks intothe other endplate 104. The fitting 322 can lock into the other endplate104 by any means known in the art such as a snap fit. In such a snapfit, the fitting 322 is capable of plastically deforming facilitated bya slit 324 and a corresponding receptacle 326 on the endplate 104. Thereceptacle 326 has a large bore 328 that accommodates a tapered noseportion 330 of the fitting 322. The receptacle 326 also has a coverplate 332 having a smaller diameter bore 334. The cover plate 332 can beintegral with the endplate 104 or separate therefrom and fastened to theendplate 104, such as by screws 333. The fitting 322 is pulled such thatthe tapered end portion 330 is plastically deformed by the smallerdiameter bore 334 until the same passes through the small diameter bore334 and is disposed in the large bore 328 where it is captured as shownin FIG. 4 c. The fitting 322 can be made of any material that is easilydeformable yet strong, such as a plastic, however, metals can also beused if the fitting 322 is configured properly to mechanically deformwith the use of the slit 324 or with multiple slits. Once the fitting322 is captured in the receptacle 326, the wire 120 is configuredsimilar to that described in FIGS. 1 a and 1 b, in that it can elongatealong with the expansion of the beam 300 or aid in the expansion of thebeam 300 if fabricated from a shape memory material, as described above.The assembly of the beam 300 having the tensile elements integratedtherein is similar to that described above with regard to FIG. 4,however, the cable 3062 and capsule 302 “necklaces” are formed with thecoiled wire 120 and fitting 322 attached thereto. The end 120 a of thewire 120 is inserted into corresponding holes 120 b in the endplate 102and fastened thereto by any means known in the art, such as brazing 120c. The other endplate 104 is then connected as discussed above with thereceptacle(s) 326 corresponding to the cable(s) 306 having the coiledwire 120 and fitting 322.

Referring now to FIG. 5 there is shown a structure, generally referredto by reference numeral 500 in which at least one component of which wasmade from an expanding foam. The structure 500 of FIG. 5 illustrates anenclosed structure that could house people or can be used for storage,however, the same can be open on one or more sides and be used invarious other ways, such as an aircraft hanger. Furthermore, althoughthe structure 500 can have a temporary nature, the same can also beconverted into a permanent structure, such as by finishing an interiorthereof with plumbing, electrical, interior walls and the like and/or anexterior thereof, such as with stucco or siding.

The structure includes several truss assemblies 200 as shown in FIG. 3to support a roof 502 (shown in dotted lines) comprised of several roofpanels 504. The structure 500 also includes two or more walls 506supported by the ground or other supporting structure. Each of the sidewalls can comprise one or more individual wall panels 508. The roof andwall panels 504, 508 can be configured similarly to the structuralmembers of FIGS. 1 a, 1 b, and 4 except they may have a greater width.For example, such roof and wall panels 504, 508 can have an elongatedlength of 8 feet and a width of 4 feet to resemble a standard 4×8 paneltypically used in construction. The panels can interlock by any meansknown in the art, such as the hook and latch arrangement described withrespect to FIG. 3 and/or any other means such as screw, bolts and/oradhesives. The panels can further have a cut-out 510 in each of its twoupper corners for accommodating the individual beams 100 of the trussassemblies 200. The cut-out 510 can be the same depth (X1) of the beamand ½ the width (X2/2) such that when two wall panels 508 are butttogether as shown in FIG. 5 a, two cut-outs 510 are disposed next toeach other to form a channel that is equivalent to the depth (X1) andwidth (X2) of the beam 100 to accommodate the same within. The beams 100can be press fit within the cut-outs 510 and/or secured with adhesives,screw, bolts, or any other means known in the art. End wall panels 512can be sized to fit within the shape defined by the wall panels 508 andtruss assembly 200 using one such shaped panel or several which conformto the shape when assembled. The end-wall panels 512 can be secured toboth the adjoining wall panels 508 and truss assemblies by any meansknown in the art, such as adhesives and/or screws, bolts and the like.The roof panels 504 can also be secured to the truss assemblies 200 byany means known in the art, such as adhesives and/or screws, bolts andthe like.

After assembly, gaps (if any) between components in the structure 500can be sealed by any means known in the art, such as with caulking orexpanding foam. The wall and end wall panels 508, 512 can be providedwith window and door openings 514, 516, respectively such that openingsfor the same are provided in the covering 106. However, such openingscan also be easily cut in the wall and end-wall panels 508, 512 afterthe same have cured with conventional tools such as a hand saw (or anelectric carving knife). Conventional windows and doors can then bedirectly disposed in the openings 514, 516 and secured to the wall andend wall panels 508, 512 by any means known in the art, such asadhesives, screws and/or bolts. Such windows and doors, a portion ofwhich is shown in FIG. 5 b and referred to by reference numeral 518, canhave a flange 520 that overlaps at least two sides, and preferably eachside of the opening 514, 516. An adhesive or caulking 522 is disposedbetween the flange 520 and the wall/end wall panel 508, 512. Fasteners,such as bolts 524 can then be disposed through the flange 520 andwall/end wall panel 508, 512 with large diameter washers 526 at each endand secured with a mating nut 528. Similar methods can be used to fastenthe roof panels 504 to the truss assemblies 200 or any other twocomponents together. The openings 514, 516 can also be trimmed with woodaround an interior periphery of the openings 514, 516, which can befastened by any means known in the art, such as adhesives, screws andthe like, and the windows and doors 518 can be fastened to the wood in aconventional manner as is known in the construction arts.

When assembling a structure 500 with elements, intermediate elements canbe assembled first in place, and then pressurized (if applicable) andthen the foam can then be released. After the structure is assembled,one may add frames or other sturdy structural elements such as columnsor beams (aluminum or steel or the like) to make a much strongerstructure. The latter elements may be added at a later time. Then theexpandable structure acts mostly as the outer skin of the structure.Alternatively, a basic frame may put up first and then the expandableelements be added to it.

As discussed above, any of the components discussed above which makes upthe structure 500 can be secured to another component by adhesives,screws, bolts, and any other means known in the art, such as thehook/latch mechanism shown in FIG. 3. Referring to FIGS. 5 c and 5 d,there is shown a structural member, generally referred to by referencenumeral 600, which is similar to beam 100, but can be any structuralmember formed by expanding foam. Such structural member 600 includesbolt fasteners 602, which after expansion of the structural member 600,protrude from a surface thereof and are secured in the foam 116.Although the bolt fasteners 602 are shown on an end surface, they can bepositioned on any expanding surface of the structural member 600 and atany location on such surfaces. Furthermore, such an arrangement may beparticularly useful on the edges of openings 514, 516 for attachment ofwindows and doors and/or on the truss assemblies 200 for fastening thesame to the roof panels 504. The bolt fasteners 602 are typically metalor strong plastic and have a loop 604 on one end thereof through whichthe wire 120 is threaded. The bolt fasteners 602 have another threadedend 606 which are threaded and protrude from the covering 106 through agrommet 608 for sealing around the bolt fastener 602. An o-ring or othersealing means may also be disposed in the grommet corresponding to anon-threaded portion of the bolt fastener. As shown in FIG. 5 d, duringelongation of the structural member 600, the bolt fasteners 602 movewith the expansion, guided by both the wire 120 and grommet 608. Aftercuring, the bolt fasteners 602 are secured in the foam 116 and can beused to secure other components or articles thereto. One or moreprojections 610 can be added to the bolt fasteners 602 at a locationcorresponding to the cavity 110 to increase their footprint and ensurethat they cannot be easily pulled from the cured foam 116. Referring nowto FIG. 5 e, there is shown an alternative embodiment of the boltfastener 602 having a plurality of projections 610. The projections 610being paddle shaped and disposed about the bolt fastener 602 to resistpulling of the bolt projection from the cured foam 116.

The structure 500 can be secured to the ground 528 or other surface byone or more cables 530 slung over the roof 502 and secured to the ground528 or other surface, such as by corkscrew stakes 532 as is known in theart. Those skilled in the art will appreciate that such a structure 500can be assembled in a short time (rapidly deployed), with nothing butthe simplest hand tools (with a minimum of labor), and require nomaintenance to maintain the stability thereof. The resulting structure500 can also be lightweight, bullet proof/resistant, fireretardant/resistant, insulated from temperature extremes, and opaque tothe sun's ultra-violet exposure. Those skilled in the art willappreciate that the span of the truss assemblies 200 can be very long,making for a spacious interior without the need for posts since they arelight weight and strong and they only support lightweight roof panels504. Therefore, such a structure can house large objects, such asaircraft without the interference of posts and other support members. Ifposts are needed to support very long spans, the same can also beexpanded using a structure similar to that shown in FIGS. 1 a and 1 b.Such posts can have any cross-section, such as square or round and donot require wires 120 since they do not carry a tensile load. However,wires 120 may be used where the posts are very long to resist bucklinggenerated tensile loads.

Referring now to FIG. 6, there is shown a side view of an expandablestructure in the form of a flotation bridge generally referred to byreference numeral 650. The flotation bridge (pontoon) is constructedfrom one or more expandable beams, similar to that shown in FIGS. 1 aand 1 b. Such beams 100 can be linked together to span longer widths W,by any means known in the art, such as the hook and latch arrangement ofFIG. 3. However, an alternative means to link the individual beams 100together may include a pivot 652 where one of the endplates 104 has aprojection 654 with a bore 656 and the other endplate 102 has aprojection 658 with a mating shaft 660. When linking the beams 100together, the shaft 660 is disposed in the bore 656 and the shaft isrotatably secured therein by any means known in the art, such as byplacing a cotter pin 662 in a hole 664 at the end of the shaft. Such anarrangement will allow for fluctuations in height between beams causedby the water 667 and/or unequal loading of the bridge 650. The pivotjoint can also be used in the configuration of FIG. 3 to attach thebeams 100 together. However, such joint would be positioned on a lowerportion of the endplates 102, 104 such that a load on the truss assembly200 would tend to close the endplates 102, 104 together.

Two or more of such beams 100 are arranged across the width W of thewater 667 substantially parallel to each other. Panels 668, similar tothose described above with regard to FIG. 5 (e.g., 4×8 expandablepanels) are then laid on top of the beams 100 and can be secured theretoby any means known in the art or described above, such as an adhesive,and/or other fastener such as the bolt fasteners described with regardto FIGS. 5 c and 5 d. The bridge assembly 650 can then float on thesurface of the water due to the exceptional buoyancy of the expandedfoam 116 in the cavities 110 of both the beams 100 and panels. Using abuoyancy of 46 pounds per cubic foot (as discussed above) each 4×8 by 1foot thick panel has a buoyancy of 1,1104 pounds. Therefore, a flotationbridge 650 having several panels 668 and beams can support significantamounts of personnel as well as light machinery. The flotation bridge650 can be secured with cables 670 secured at one end to an eyehook 672and at another end to a corkscrew stake 674 secured to the ground 676.The eyehook 672 can be mounted to either the endplate 102, 104 of thepanels 658 and/or beams 100 such as by providing a threaded hole on theendplates 102, 104 and a mating threaded stud on the eyehook 672.Several of such cable arrangements can be provided to secure andstabilize the flotation bridge 650. Although not shown, ramps havingtapered endplates may be provided at each end of the flotation bridge tomake for a smooth transition between the ground 676 and the panels 658.Such tapered ramps may also be constructed similarly to the structuralmembers 100 shown in FIGS. 1 a, 1 b and 4 in which the same is expanded.Although expandable panels would provide greater buoyancy, the panelscan be any conventional materials such as wood, plastics or cement.

Referring now to FIGS. 7 a, 7 b, 7 c, 7 d, 7 e and 7 f there isillustrated an expandable structure in the form of a ladder, which isgenerally referred to by reference numeral 700. The ladder is comprisedof two expandable structural members 702, which carry rungs 704.Although the rungs 704 can also be expandable, they are preferablyformed out of a solid material, such as wood, plastic or metal, sincethey are essentially compact in their solid form and can carry a greaterload in such form. Although shown having a circular cross section, therungs can have any other cross section known in the art. The structuralmembers 702 are configured similarly to that of the beams of FIGS. 1 a,1 b and 4 with endplates 102, 104, covering 106 and possibly wires 120.The wires 120 are utilized because when placed at an angle againstsomething to be climbed, the portion of the structural members 702facing the thing to be climbed is in tension and such wires 120 aid incarrying the tensile load therein. The structural members 702 furtherhas grommets 706 disposed in or on the covering 106 and preferablyspaced at equal intervals for supporting the rungs 704.

Referring now to FIGS. 7 d and 7 e, the grommets 706 have a bore 708 foraccommodating the cross-sectional shape of the rungs (at least at theends of the rungs which may differ from the cross-sectional shape of acentral portion of the rungs). The bore 708 can be a blind hole orthrough hole as shown in FIGS. 7 d and 7 e. The grommets 706 preferablyhave a flange 710 on each side thereof for overlapping with the cover106. The cover 106 is preferably attached to the grommet 706 at theflange 710 by any means known in the art, such as by adhesives,heat-sealing, or fasteners. One of the flanges 710 can be separate froma body 712 of the grommet 706 and attached by any means known in theart, such as by mating threads 714 to facilitate assembly of thegrommets 706 to the cover 106. In addition to the wires 120 used forcarrying at least a portion of any tensile load carried by thestructural member 702, wires 716 can also be used between the endplates102, 104 and adjacent grommets 710 and between adjacent grommets 710.Such wire 716 is useful to assist in carrying a load applied to therungs 702. After expansion of the structural member 702, the foam 116will envelope each of the grommets 706 and secure it in place. If notfor the wires 716, any load applied to the rungs 704 is carried incompression by the foam between adjacent rungs 704. However, with theaddition of the wires 716, a large portion of any load applied to a rung704 is carried by the wires 716 in tension. The wires 710 can beattached to the endplates as described above and can be attached to thegrommet body 712 by any means know in the art such as by brazing.Alternatively, the wire can be one piece and may simply be wound one ormore times around each grommet 706.

After expansion of two structural members 702, which act as legs of theladder 700, the ends 704 a of the rungs are inserted into the bores 708of the grommets 706 to form the ladder 700. The rung ends 704 a may bepress fit into the bores 708 or have some type of positive locking meanssuch as that shown in FIG. 7 f. FIG. 7 f shows the rung end 704 a havinga step 704 b and a hole 704 c with a cotter pin 718 being disposed inthe hole 718 to positively retain the rung 704 in the bore 708 of thegrommet 706. After assembly, the ladder 700 can be used to climb up ordown and since the same is buoyant, the ladder 700 can also float onwater and support the weight of a person crossing the water. If theladder is configured similarly to that shown in FIG. 4, the same can becompact enough to be carried in a backpack of a person and can expand upto 30 times the compact size. Although not shown, additional items canbe attached to the endplates, such as footings on the bottom endplatesor cushions on the top endplates, as is known in the art. Such items canbe attached by any means known in the art, such as adhesives, screws orbolt fasteners.

Referring now to FIGS. 8 a, 8 b, and 8 c, there is shown anelectronic/electrical device which can be expanded using the expandablefoams discussed above, the device being referred to by reference numeral800. Although such device 800 is shown and described as a communicationdevice, such is shown by way of example only and those skilled in theart will appreciate that the electrical/electronic devices can take manyforms, such as a microwave oven, or scientific equipment. The device 800is shown in its compact form in FIGS. 8 a and 8 b in front and sideviews, respectively, such that it can be easily carried by a person,such as in a backpack. The device can be made to expand similarly to thestructural member 100, 300 of FIGS. 1 a, and 4, respectively. The devicehas a body portion 802 and an antenna dish portion 804, which afterexpansion, unfolds from the body portion 802 as shown in FIG. 8 c. Thebody portion 802 has embedded or disposed thereon a power supply 806 andelectronics used for operation of the device, shown schematically in theform of a control panel 808. The control panel 808 is electricallyconnected to the power supply 806 and the antenna dish 804 with wiring810 that can expand with the component portions, such as being coiled.The power supply 806 could be a battery. However since batteries have alimited shelf life, the power supply 806 can also generate power fromthe environment such as a photovoltaic cell, or thermophotovoltaic cellthat can supply power directly to the electrical/electronic componentsor for storage in a storage device, such as a battery or a capacitor. Inthe case of a thermophotovoltaic cell, the same can generate power fromthe exothermic heat from the foam reaction. Such power can besupplemented by other power sources. Other components, if sensitive toheat, can be insulated from the exothermic heat generated by the foamreaction to avoid damaging the same.

Referring now to FIGS. 9 a, 9 b, and 9 c, there is shown an expandingmember for use with dropping machinery for at least partially absorbingan impact of the machinery with a surface, such as the ground (orwater), the member being generally referred to by reference numeral 900.Although, the member 900 is shown and described with regard to droppinga tank 902 from the fuselage of an aircraft 904, such is given by way ofexample only. Those skilled in the art will appreciate that any type ofobject or machinery can be dropped utilizing member 900 from a heightonto a surface. Although not shown, the tank 902 can also have aparachute or like device for decreasing its velocity upon impact withthe surface.

The tank 902 is shown as being secured to a pallet 906 or like articleas is known in the art which is movable upon a base 908, such as a railfor guiding the tank 902 towards an open end of the fuselage. The member900 is attached to the pallet 906 at a lower end thereof, but may alsobe attached to other surfaces of the pallet 906, such as a side thereofor to the tank itself. The means for attachment can include a flange oradhesive. Attachment of the member 900 to the pallet 906 may alsoinclude integrally forming the member 900 with the palette 906. Themember 900 can be constructed as shown in FIG. 4 having a plurality ofcapsules 302, a cable 306 with mixing means 308 and a loop 310. Themember may be constructed with or without one or both of the endplates102, 104. The member 900 is configured such that expansion thereof willoccur in the direction indicated by arrows y. The aircraft 904 furtherhas a drop cable 910, which is threaded through the loop 310. The dropcable 910 terminates at a post 912 proximate the opening in the fuselagesuch that it does not impede the progress of the tank 902 and palette906 toward the open end or from the open end. Although one member 900 isshown two or more can be disposed on each of the two sides of thepalette 906 and/or along a lower surface of the palette 906. In such aconfiguration, a drop cable 910 can be provided for each member 900 or asingle drop cable 910 can be linked to each of the loops 310corresponding to each member 900.

Referring now to FIG. 9 b, as the tank 902 with attached palette 906 isadvanced through the opening in the fuselage, the post 912 and dropcable 910 capture the loop 310 to prevent its forward progress therebycausing a relative movement of the cable 306 and the member 900. Thecable 310 can be completely withdrawn from the cavity 110 or the loop310 can fail and release from the post 912 after the cable 310 is fullywithdrawn through the cavity 110. Such relative movement between thecable 310 and member 900 causes the capsules 302 containing the twoparts (A and B) of expanding foam to rupture and mix, initiating thereaction thereof. The initiation of the reaction can be delayed byextending the distance between the loop 310 and the member 900. As shownin FIG. 9 c, the member expands in the y direction prior to impact ofthe tank 902 with the ground 914 or other surface. An additive can beadded to the capsules such that the foam 116 in the cavity does notfully cure (and harden) prior to impact. However, the combination ofcold temperature at the altitude of the drop along with the expecteddrop times should not necessitate the addition of such additives.However, such additives may be used to provide maximum expansion withoutappreciable hardening of the foam. Upon impact, the covering 106 canfail such that the uncured foam can be released from the cavity 110 toabsorb the impact. Perforations 916 can be provided in the covering 106to facilitate and/or control such failure. Relief valves can also beprovided in the covering 106 to allow the uncured foam to escape thecavity 110 upon impact in a controlled manner. Such relief valves can besimple spring valves with ball seats that are disposed in the coveringsimilarly to the grommets 608 discussed above. If the surface 914 iswater, additives may be added to the capsules to accelerate curing ofthe foam so that the member is fully buoyant upon impact with the watersurface. Alternatively, the tank 902 or other object can be at leastpartially submerged in the water after impact and can rise to thesurface upon full expansion and curing of the foam in the member(s) 900.Thus, a member useful for reducing the impact with the ground and/orproviding buoyancy upon impact with a water surface can be providedwhich does not occupy additional space in the fuselage of an aircraft.

Referring now to FIG. 10 a, there is shown a sectional side view of anexpanded structural member generally referred to by reference numeral1000. The expanded structural member 100 can have any of the featuresdescribed above and further has shape restraint members 1002 forconstraining a cross-section of the member 1000 to a predeterminedshape. As shown in FIG. 10 a, the shape restraint members 1002 can bespaced along a length L of the expanded structural member 1000. Theshape restraint members 1002 are preferably wires made from any suitablematerial, such as metal or natural or synthetic fiber and fastened ateach end thereof to the covering 106 by any means known in the art. Suchas by tying a knot on the exterior of the covering 106, clips, staples,sewing and the like. As shown in FIG. 10 b, the shape restraint members1002 are disposed along the cross section in various lengths toconstrain the shape of the cross section. In the embodiment shown inFIG. 10 b, the cross-section is shown as an oval, however, those skilledin the art will appreciate that any cross sectional shape is possible,such as an I-beam shape, circle, square, rectangle and the like. Theshape restraint members 1002 can also be used with the members describedabove instead of a roller or form.

As an alternative to the shape restraint members 1002, frames (notshown) with the desired cross-sectional geometry may be attached atregular intervals along the length L of the beam member inside thecovering 106. As the expanding foam 116 is released, the above frameswould then constrain the beam cross-section to near the desiredgeometry.

When the beam member is to be cylindrical with a circular cross-section,the foam material is desired to be formed at the wall surfaces since thefoam material positioned near the center of the member carries minimalbending load. Such beam elements are constructed best by sealing theirends (e.g., with end plates 102, 104), pressurizing their interior space110 and then releasing the expanding foam 116 around the interiorsurfaces. A hollow cross-sectional shape, (e.g., where the foam isconcentrated near the walls (covering 106)) can be readily achieved byhaving spread the base chemicals (parts A and B) over the interior ofthe covering and protecting it by a thin membrane (and a membranebetween parts A and B). Once the element is pressurized, the membraneseparating the chemicals can be released using one of the describedtechniques.

Other features may be used with any of the embodiments discussed above,for example, gas generating additives can be added the foam parts (A andB), so that once they are released by the removal or puncturing of amembrane, the foam parts are mixed and blown up by the generated gas.Any fabric made ropes and/or covering material can also soaked in foamand is thereby hardened and capable of taking compressive loads. Thecovering may contain reinforcing fibers oriented in the direction ofmaximum stress. The internal sealed volume of a member withnon-permeable covering can be pressurized first to subject thelongitudinal wires 120 (preferably springs or elastic materials thatwould significantly stretch during the pressurization press arepreferred since a light reduction in length would not significantlyreduce the preloading force level) to tensile stress. Since thecross-sectional area of the members is usually large, then one can exertlarge tensile forces on these elastic elements. Then when the beam (topsurfaces) or column element is subjected to compressive loads, thetensile preload has to be overcome before the foam and lining materialis subjected to compressive loads (the lining and foam assembly isweakest in compression). One could also use “wires” in the lateral andother general directions so that as a whole, the applied loads areoptimally supported.

While there has been shown and described what is considered to bepreferred embodiments of the invention, it will, of course, beunderstood that various modifications and changes in form or detailcould readily be made without departing from the spirit of theinvention. It is therefore intended that the invention be not limited tothe exact forms described and illustrated, but should be constructed tocover all modifications that may fall within the scope of the appendedclaims.

1. A ladder comprising: first and second expandable members, each of thefirst and second expandable members comprising: a covering capable ofexpansion, the covering defining a cavity; and expansion means forexpanding foam in the cavity in an expansion direction to expand thecovering into a predetermined shape; each of the first and secondexpandable members having a plurality of holes; and a rung, having afirst end disposed in each of the plurality of holes of the firstexpandable member and a second end disposed in a corresponding hole inthe second expandable member.
 2. The ladder of claim 1, wherein thecovering is pleated when compact.
 3. The ladder of claim 1, furthercomprising first and second endplates, the covering being disposedbetween the first and second endplates.
 4. The ladder of claim 3,wherein the expansion means comprises: a first inlet formed in one ofthe first and second endplates, the first inlet being in communicationwith the cavity; and a source in communication with the first inlet forsupplying foam in a liquid state to the cavity via the first inlet. 5.The ladder of claim 4, further comprising: a second inlet formed in oneof the first and second endplates, the second inlet being incommunication with the cavity; and a gas source in communication withthe second inlet for supplying gas to the cavity via the second inletfor at least one of pre-expanding the covering and facilitating fillingof the cavity with the foam.
 6. The ladder of claim 1, furthercomprising bulge prevention means for preventing bulging of the coveringin a direction other than the expansion direction.
 7. The ladder ofclaim 1, further comprising one or more tensile elements disposed in thecavity for carrying at least a portion of a tensile load on the firstand second expandable members.
 8. The ladder of claim 1, wherein theexpansion means comprises: first and second capsules disposed in thecavity, the first capsule having a first liquid therein, the secondcapsule having a second liquid therein, the first and second liquidswhen combined reacting to form the foam; and means for mixing the firstand second liquids.
 9. The ladder of claim 8, wherein the means formixing comprises: the first and second capsules having a skinencapsulating the first and second liquids, respectively; and a cablehaving the first and second capsules formed thereon, the cable having amixing means disposed on the cable, the cable being capable of beingwithdrawn through the cavity such that the skin is broken and the mixingmeans facilitates mixing of the first and second liquids.
 10. The ladderof claim 9, wherein the cable further comprises: one or more wires forcarrying at least a portion of a tensile load on the member, each of theone or more tensile elements being capable of being expanding in theexpansion direction and being connected to one of the first and secondendplates at a first end and being connected to the cable at a secondend; and means for fixing the second end to the other of the first andsecond endplates upon expansion of the one ore more wires.
 11. Theladder of claim 1, further comprising a grommet disposed in each of theplurality of holes.
 12. The ladder of claim 11, further comprising aconnection means for connecting each of the grommets together such thatthey react to an applied force as a unitary member.
 13. The ladder ofclaim 12, further comprising first and second endplates, the coveringbeing disposed between the first and second endplates, wherein theconnection means comprises a wire connected between each of the grommetsand between at least one of the first and second endplates and at leastone of the grommets.
 14. The ladder of claim 13, wherein the wire isconnected between each of the grommets by winding the wire around anoutside circumference of the grommet.
 15. The ladder of claim 1, furthercomprising locking means for locking the rungs in the plurality ofholes.